text: def to_openmm_Modeller(item, selection='all', frame_indices='all', syntaxis='MolSysMT'):
  
      from molsysmt.tools.file_prmtop import is_file_prmtop
      from molsysmt.basic import convert
  
      if not is_file_prmtop(item):
          raise ValueError
  
      tmp_item = convert(item, 'openmm.Modeller', selection=selection, frame_indices=frame_indices, syntaxis=syntaxis)
  
      return tmp_item
  
  